1. Field of the Invention
This invention pertains generally to agricultural tool bars.
2. Description of the Prior Art
In tool bars having wings that are foldable from an extended transverse ground working position to a narrow transport position, it has become common to install the hydraulic cylinder for each wing inside the hollow tool bar to avoid tool conflict. Where a tool bar wing is to be folded more than 90.degree., rollers are required to support the rod end of each cylinder and an extra link or links between the rod end and an ear on the tool bar wing is required. By careful sizing of the rollers in the tool bar and a lost motion connection, preferably between the link and the rod end, wing fall can be substantially reduced while providing a smooth folding capacity of about 180.degree. so that the folded wing lies on the tool bar central section.
A problem, however, occurs when a heavy large wing is to be folded and unfolded because of the limited length possible of the link in the tool bar. Especially in the unfolding process wherein the upper hinge pivot between wing and central section is used as a fulcrum, the effective lever length of the link to the rod end is small and hence higher hydraulic pressure may be necessary than is normally provided by the tractor. Also, when the cylinder rod is extended as the wing is initially lifted, a greater level action is desirable.